BiOCI pigment

ABSTRACT

A bismuth oxychloride effect pigment has a carbon black particulate at about the surface of the crystals of the bismuth oxychloride. The pigment is prepared by, for instance, growing the bismuth oxychloride crystals, and adding the particulate before the hydrolysis is complete.

BACKGROUND OF THE INVENTION

Laminar or plate-like pigments which impart a pearly or nacreous lusterinto objects on which or in which they are used are known as “effect”pigments, and have also been known as pearlescent pigments or nacreouspigments. These effect pigments include naturally occurring substancessuch as pearlescence, a mixture of guanine and hypoxanthine which isobtained from the scales of fish, as well as various syntheticmaterials. The effect pigments which are most often encounteredcommercially are titanium dioxide-coated mica and iron oxide-coatedmica. Other synthetic effect pigments which have been developed for bothcosmetic and industrial use include materials such as bismuthoxychloride and lead carbonate.

Bismuth oxychloride has been used as an effect pigment in a number offields. It is used, for instance, as a pigment in cosmetics, such asnail enamels and lipsticks, and it is also used to pigment plastics andpaints. In order to extend the range of applications, bismuthoxychloride pigments have been coated with such materials as 2-hydroxybenzophenones and rare earth metals in order to impart ultravioletstability or weather fastness properties to the effect pigment. See,e.g., U.S. Pat. No. 5,149,369. The result of coating a BiOCl pigmentitself, however, is that some of the natural luster and brightness islost.

Another coated pigment described heretofor is a coated substrate inwhich the coating contains carbon black embedded in BiOCl. See, U.S.Pat. No. 4,076,551. The substrate can also be BiOCl.

While it is possible to prepare a BiOCl pigment containing carbon black,the carbon black is labile in that it can be easily lost during ordinaryhandling of the pigment. As a result, the metallic black effect of thecarbon black is diminished or lost.

It is accordingly the object of the present invention to provide animproved bismuth oxychloride effect pigment with better stability,including light stability and brightness, and to provide a method forproducing such a pigment.

SUMMARY OF THE INVENTION

The present invention relates to an improved bismuth oxychloride effectpigment and a process for its production. More particularly, theinvention relates to an improved bismuth oxychloride effect pigmenthaving a “locked-in” embedded particulate of carbon black at about thesurface thereof, which can be produced by hydrolyzing a soluble bismuthsalt in the presence of chloride, adding the particulate to thehydrolyzation reaction mixture and then adding an aluminum or rare earthmetal salt.

DESCRIPTION OF THE INVENTION

In accordance with the present invention, the conventional production ofbismuth oxychloride crystals is modified by employing a carbon blackparticulate and thereafter adding an aluminum or rare earth metal saltto lock in (cement) the particulate to the crystal.

Bismuth oxychloride crystals are typically produced by combining asoluble bismuth compound with a source of chloride under acidconditions. Hydrolyzation occurs at a rate which is dependent on theconcentrations of the reactants, pH and temperature. The material whichis most often employed is bismuth nitrate although any soluble bismuthcompound can be used. To prevent premature hydrolysis and precipitationof insoluble bismuth compounds, the bismuth salt is usually employed inthe form of an aqueous acidic solution. For this purpose, the solutiontypically contains a compatible mineral or other strong acid.Hydrochloric acid and a mixture of hydrochloric and nitric acids areparticularly convenient since they serve as a source of the chlorideions which are used to form the bismuth oxychloride. The bismuthcompound is hydrolyzed by maintaining the acidity within desired limits,usually about pH 1, by adding a suitable base to neutralize acid whichforms during the hydrolysis reaction. The base most often used is analkali metal hydroxide, particularly sodium hydroxide, but other solublesources of hydroxyl ions, such as a strongly basic amine or a baseprecursor such as urea, can also be used.

The preparation of the bismuth oxychloride crystals is generallyeffected at a temperature between about 50° C. and 100° C. and morepreferably about 60-80° C. Usually the soluble bismuth salt solution andthe base are pumped into an aqueous acidic reservoir. Any desiredbismuth oxychloride crystal size can be realized by regulating theamount of the bismuth solution which is used.

In a preferred procedure, a preformed particulate is added to thehydrolyzation reaction mixture before the formation of the desiredbismuth oxychloride crystals is complete. So that the particulate is ator near the surface of the effect pigment, the bismuth oxychlorideformation process is allowed to achieve about 80 to 95% completion,preferably about 85 to 90% completion, before the addition is effected.The particulate is carbon black having a particle size of less thanabout 500 nm. The particle size of the particulate is usually at leastabout 5 nm, preferably at least about 10 nm and most preferably at leastabout 100 nm. While the particulate can be added as such, it isgenerally more convenient to disperse the particulate in a compatibleliquid such as water or, more preferable, the liquid in which thebismuth salt was dissolved. The concentration of the particulate in theresulting slurry can be varied as desired and the viscosity is generallythe controlling factor, with that which allows easy processing of theslurry being selected. Typically, the concentration of the particulatein the slurry is about 1 to 40%. Alternatively, it is possible to finishthe BiOCl crystal formation before adding the particulate. In this case,the pH is usually raised to, for instance, at least about 2 to easematerials handling and then a dispersion of the particulate is added.

Next, a rare earth metal salt or an aluminum salt, or a combination ofsalts, is introduced into the slurry and the pH is further raised to aneffective deposition value, for example, to at least about 7 in the caseof an aluminum salt and to at least about 8 (and preferably at leastabout 10) in the case of a rare earth metal salt. The nitrate is thepreferred salt. While any rare earth metal can be used, it is preferredto employ cerium.

The amount of the particulate added to the bismuth oxychloride slurry ineither process is such that the particulate will generally range fromabout 0.5 to 20 weight percent, preferably about 1 to 5 weight percent,based on the weight of the bismuth salt being employed. This results inthe incorporation of about 1 to 20 weight, preferably about 5 to 15weight percent, particulate based on the total weight of the finalpigment. Since the particulate is “locked-in”, it is embedded or boundto the effect pigment at or near the BiOCl surface but does not form asmooth and continuous coating on that surface. As a result, the inherentbrightness of the BiOCl effect pigment is substantially retained whileat the same time, a new effect with an improved light stability isachieved. The “lock-in” procedure diminishes to tendency of the carbonblack to be lost during subsequent handling of the effect pigment.

At the end of the BiOCl preparation, the resulting pigment is recoveredfrom the slurry in which it was formed in any convenient fashion. Forexample, the pigment can be filtered and then washed with water untilsubstantially free of salt. Alternatively, a settling and decantingprocedure can be employed. The pigment can be dried by heating ifdesired.

The resulting BiOCl effect pigment is thereafter processed in theconventional manner into various types of finished products. Forexample, the filter cake can be dried to produce a powdered producteither with or without the addition of a dispersing agent.Alternatively, the filter cake can be flushed with an oil such as castoroil or mineral oil, which causes the pigment originally wet with waterto become a pigment wet with oil.

The resulting bismuth oxychloride can be employed in the same manner asthe previously known bismuth oxychloride effect pigments have beenemployed. For example, it can be used in cosmetics as well as paints andcoatings. The plurality of crystals in the products made by the presentinventive process have been found to be more homogeneous thanconventional bismuth oxychloride effect pigments, combining brightnesswith enhanced ultraviolet light stability. This increases the ability touse the material in automotive paint and other outdoor applications.

Products of this invention have an unlimited use in all types ofautomotive and industrial paint applications, especially in the organiccolor coating and inks field where deep color intensity is required. Forexample, these pigments can be used in mass tone or as styling agents tospray paint all types of automotive and non-automotive vehicles.Similarly, they can be used on allclay/formica/wood/glass/metal/enamel/ceramic and non-porous or poroussurfaces. The pigments can be used in powder coating compositions. Theycan be incorporated into plastic articles geared for the toy industry orthe home. These pigments can be impregnated into fibers to impart newand esthetic coloring to clothes and carpeting. They can be used toimprove the look of shoes, rubber and vinyl/marble flooring, vinylsiding, and all other vinyl products. In addition, these colors can beused in all types of modeling hobbies.

The above-mentioned compositions in which the compositions of thisinvention are useful are well known to those of ordinary skill in theart. Examples include printing inks, nail enamels, lacquers,thermoplastic and thermosetting materials, natural resins and syntheticresins. Some non-limiting examples include polystyrene and its mixedpolymers, polyolefins, in particular, polyethylene and polypropylene,polyacrylic compounds, polyvinyl compounds, for example polyvinylchloride and polyvinyl acetate, polyesters and rubber, and alsofilaments made of viscose and cellulose ethers, cellulose esters,polyamides, polyurethanes, polyesters, for example polyglycolterephthalates, and polyacrylonitrile.

For a well-rounded introduction to a variety of pigment applications,see Temple C. Patton, editor, The Pigment Handbook, volume II,Applications and Markets, John Wiley and Sons, New York (1973). Inaddition, see for example, with regard to ink: R. H. Leach, editor, ThePrinting Ink Manual, Fourth Edition, Van Nostrand Reinhold(International) Co. Ltd., London (1988), particularly pages 282-591;with regard to paints: C. H. Hare, Protective Coatings, TechnologyPublishing Co., Pittsburgh (1994), particularly pages 63-288. Theforegoing references are hereby incorporated by reference herein fortheir teachings of ink, paint and plastic compositions, formulations andvehicles in which the compositions of this invention may be usedincluding amounts of colorants. For example, the pigment may be used ata level of 10 to 15% in an offset lithographic ink, with the remainderbeing a vehicle containing gelled and ungelled hydrocarbon resins, alkydresins, wax compounds and aliphatic solvent. The pigment may also beused, for example, at a level of 1 to 10% in an automotive paintformulation along with other pigments which may include titaniumdioxide, acrylic lattices, coalescing agents, water or solvents. Thepigment may also be used, for example, at a level of 20 to 30% in aplastic color concentrate in polyethylene.

In the cosmetic field, these pigments can be used in the eye area and inall external and rinse-off applications. Thus, they can be used in hairsprays, face powder, leg-makeup, insect repellent lotion, mascaracake/cream, nail enamel, nail enamel remover, perfume lotion, andshampoos of all types (gel or liquid). In addition, they can be used inshaving cream (concentrate for aerosol, brushless, lathering), skinglosser stick, skin makeup, hair groom, eye shadow (liquid, pomade,powder, stick, pressed or cream), eye liner, cologne stick, cologne,cologne emollient, bubble bath, body lotion (moisturizing, cleansing,analgesic, astringent), after shave lotion, after bath milk andsunscreen lotion.

For a review of cosmetic applications, see Cosmetics: Science andTechnology, 2nd Ed., Eds: M. S. Balsam and Edward Sagarin,Wiley-Interscience (1972) and deNavarre, The Chemistry and Science ofCosmetics, 2nd Ed., Vols 1 and 2 (1962), Van Nostrand Co. Inc., Vols 3and 4 (1975), Continental Press, both of which are hereby incorporatedby reference.

In order to further illustrate the invention, various examples are beingset forth below. In these examples as well as throughout the balance ofthis specification and claims, all temperatures are in degreesCentigrade and all parts and percentages are by weight unless otherwiseindicated.

EXAMPLE 1

A sufficient quantity of concentrated hydrochloric acid was introducedinto a demineralized water reservoir to bring the pH of the resultingreservoir to about 1. After the reservoir had been heated to about 70°C., 400 milliliters of an aqueous solution containing hydrochloric acidand 0.2 g/ml of bismuth nitrate was pumped into the reservoir at a rateof 5 ml/minute. Simultaneously, a 20% aqueous sodium hydroxide solutionwas added to the reservoir in order to neutralize the acid which wasbeing formed during the hydrolysis reaction.

The hydrolysis reaction under these conditions generally take about 80minutes for the BiOCl formation to be complete. After about 72 minuteshad elapsed, 28 grams of an aqueous slurry containing 30% of carbonblack (about 100 nm particle size) was introduced into the aqueousbismuth oxychloride crystal slurry and then the hydrolysis reaction wasallowed to continue to completion. This took about an additional 8minutes. Then, 3.75% of Ce(NO₃)₃ was added and the pH was raised to 10with aqueous sodium hydroxide. After about 10 minutes, the resultingpigment was recovered by concentrating the crystals present in theaqueous phase of the slurry by settling and removing the supernatant.

In order to evaluate the resulting pigment for light stability, thecrystals are flushed into an organic phase which consisted of a ketoneester and aromatic solvents, followed by being dispersed in an organicsoluble resin at a crystal content of 60% by weight. Thereafter thedispersed crystals are incorporated into anacrylic-melamine/formaldehyde baking enamel such that the amount ofcrystals in the enamel is 10% weight of the total resin solids in theenamel. The enamel dispersion is then sprayed on Bonderite 40 treatedcold rolled and polished steel panels primed with a low film buildcathodic electrodeposition primer. Wet on wet coats were applied so thatthe dried film thickness is in the range of about 0.002 to 0.003 cm(about 0.9 to 1.1 mils). This is followed by an acrylicmelamine/formaldehyde clear coat of about 0.04 to 0.05 cm (about 1.5 to2 mils) dry film thickness. The panels are then baked for 30 minutes at250° F. in a forced air oven.

An evaluation test is carried out by placing partly masked panels in aCleveland chamber and exposing them to alternate cycles of 8 hours ofultraviolet light exposure and 4 hours of water condensation for oneweek. Changes in appearance of the panels were characterized bymeasuring the CIE L*a*b* values. This system is described in the text“The Measurement of Appearance”, 2nd ed., Hunter and Harold, editors,John Wiley & Sons, 1987. The system involves measuring alightness-darkness component designated L*, a red-green componentdesignated a* and a yellow-blue component designated b*. The differencein color, designated DE* is calculated using the equation

DE*=[(DL*)²+(Da*)²+(Db*)²]^(½)

in which DL*, Da* and Db* represents the difference in L*, A* and b*values between the exposed and unexposed sections of the panel. Thehigher the value of DE*, the greater the change in appearance betweenthe exposed and unexposed sections of the panel. Conversely, a lower DE*indicates increased light stability. A DE* of less than 1 is generallynot apparent to the naked eye.

The DE* of a panel using the pigment of this example was 1.0 compared toa value of 7.1 realized using a BiOCl without particulate.

EXAMPLE 2

The procedure of Example 1 is repeated except that the cerium nitrateaddition procedure was omitted. The handling of the pigment in thecourse of preparing the panels resulted in a loss of the black additiveas was apparent visually. Very severe agglomeration was apparent on thesprayed steel panels.

EXAMPLE 3

The procedure of Example 1 is repeated except that the particulateslurry employed was a 5% aqueous slurry of carbon black having aparticle size of 200 nm.

EXAMPLE 4

The pigment preparation procedure of Example 1 is repeated except thatbefore recovering the crystals from the aqueous phase of the slurry,3.75% of Ce(NO₃)₃ was added and the pH was raised to 10 with aqueoussodium hydroxide.

EXAMPLE 5

The procedure of Example 1 is repeated except that a 3.75% solution ofaqueous aluminum nitrate is used in place of the cerium nitrate and thepH is raised to 7 with aqueous sodium hydroxide rather than to 10.

EXAMPLE 6

The dried pigment of Example 1 can be formulated into a powder eyeshadow as follows:

The following materials are thoroughly blended and dispersed:

Ingredients wt parts Mearltalc TCA ® (Talc) 18 Mearlmica ® SVA (Mica) 20Magnesium Myristate 5 Silica 2 Cloisonné ® Red 424C (red TiO₂-coatedmica) 20 Cloisonné ® Violet 525C (violet TiO₂-coated mica) 13Cloisonné ® Nu-Antique Blue 626CB 2 (TiO₂-coated mica/iron oxide-coatedmica) Cloisonné ® Cerise Flambé 550Z (iron 2 oxide-coated mica)Preservatives & Antioxidant q.s.

Then 7 parts of octyl palmitate and 1 part of isostearyl neopentanoateare heated and mixed until uniform, at which time the resulting mixtureis sprayed into the dispersion and the blending continued. The blendedmaterial is pulverized and then 5 parts of Cloisonne Red 424C and 5parts of the coated BiOCl added and mixed until a uniform powder eyeshadow is obtained.

EXAMPLE 7

The dried pigment of Example 1 can be formulated into a lipstick asfollows.

The following amounts of the listed ingredients are placed into a heatedvessel and the temperature raised to 85±3° C.

wt parts Candelilla Wax 2.75 Carnauba Wax 1.25 Beeswax 1.00 Ceresine Wax5.90 Ozokerite Wax 6.75 Microcrystalline Wax 1.40 Oleyl Alcohol 3.00Isostearyl Palmitate 7.50 Isostearyl Isostearate 5.00 Caprylic/CapricTriglyceride 5.00 Bis-Diglycerylpolyalcohol Adipate 2.00 AcetylatedLanolin Alcohol 2.50 Sorbitan Tristearate 2.00 Aloe Vera 1.00 Castor Oil37.50 Red 6 Lake 0.25 Tocopheryl Acetate 0.20 Phenoxyethanol,Isopropylparaben, 1.00 and butylparaben Antioxidant q.s.

A mixture of 13 parts of the coated BiOCl and 1 part of kaolin are addedand mixed until all of the BiOCl is well dispersed. Fragrance is addedas desired and mixed with stirring. The resulting mixture is poured intomolds at 75±5° C., allowed to cool and flamed into lipsticks.

Various changes and modifications can be made in the process andproducts of this invention without departing from the spirit and scopethereof. The various embodiments which were disclosed herein were forthe purpose of further illustrating the invention but were not intendedto limit it.

What is claimed is:
 1. An effect pigment which comprises bismuthoxychloride effect pigment crystals having a preformed carbon blackparticulate embedded at about the surface thereof and containing asufficient amount of at least one of aluminum and a rare earth metal toretard loss of the particulate from the pigment.
 2. The effect pigmentof claim 1 in which the particulate is about 0.5 to 20 weight percent ofthe total weight of the pigment.
 3. The effect pigment of claim 2 inwhich the particulate is about 1 to 5 weight percent of the total weightof the pigment.
 4. The effect pigment of claim 1 containing cerium. 5.The effect pigment of claim 1 containing aluminum.
 6. In a coatingcomposition including a pigment, the improvement which comprises saidpigment being an effect pigment of claim
 1. 7. In a plastic compositionincluding a pigment, the improvement which comprises said pigment beingan effect pigment of claim
 1. 8. In a cosmetic composition including apigment, the improvement which comprises said pigment being an effectpigment of claim
 1. 9. A method of producing a bismuth oxychlorideeffect pigment which comprises combining a soluble bismuth salt andchloride ions in an aqueous medium under hydrolyzing conditions to forman aqueous dispersion of bismuth oxychloride effect pigment crystals,adding a preformed carbon black particulate to the aqueous dispersion,combining at least one salt of aluminum or rare earth metal with theparticulate-containing dispersion, and raising the pH.
 10. The processof claim 9 in which the particulate is added when about 80 to 95% ofcrystals formation is complete.
 11. The process of claim 10 in which theamount of particulate is about 0.5 to 20 weight percent based on theweight of the bismuth salt.
 12. The process of claim 11 in which theamount of particulate is about 1 to 5 weight percent based on the weightof the bismuth salt.
 13. The process of claim 11 in which the saltcombined with the particulate-containing dispersion is a nitrate. 14.The process of claim 13 in which the rare earth metal is cerium and thepH is raised to at least about
 8. 15. The process of claim 13 in whichthe salt combined with the particulate-containing dispersion is aluminumnitrate and the pH is raised to at least about
 7. 16. The process ofclaim 9 in which the particulate is added when the crystal formation iscomplete.
 17. The process of claim 16 in which the amount of particulateis about 0.5 to 20 weight percent based on the weight of the bismuthsalt.
 18. The process of claim 17 in which the amount of particulate isabout 1 to 5 weight percent based on the weight of the bismuth salt. 19.The process of claim 9 in which the amount of particulate is about 0.5to 20 weight percent based on the weight of the bismuth salt.
 20. Theprocess of claim 9 in which the amount of particulate is about 1 to 5weight percent based on the weight of the bismuth salt.
 21. The processof claim 9 in which the salt combined with the particulate-containingdispersion is a nitrate.
 22. The process of claim 9 in which the rareearth metal is cerium and the pH is raised to at least about
 10. 23. Theprocess of claim 9 in which an aluminum salt is combined with theparticulate-containing dispersion and the pH is raised to at least about7.